Use of digital telephony has become pervasive during the past decade. As the use of digital telephony expands, users expect to have all of the functionality available to them on previous analog based devices, and of course also receive the benefits associated with integration of a digital telephone with other digital networks, such as the internet. As digital telephones have become increasing mobile, it has become more challenging to determine a location of a digital telephone when a call is initiated. Some digital telephone devices include built in GPS positioning systems, and position information derived from these systems may be included in digital information provided with a call initiation request, such as a session initiation protocol (SIP) invite message. Other digital telephony platforms, such as laptop or desktop computers, may not include integrated positioning systems, such as a GPS receiver. As such, calls placed from these devices may be unable to determine their position. This technical problem may become more acute when these digital telephony platforms are used to place emergency calls. Many government agencies are requiring location information to be included with emergency calls. In some cases, emergency calls may be rejected unless the location information for an originator of the call is sufficiently precise. Therefore, improved methods of obtaining location information for callers using a digital telephone are desired.
The approaches described in this background section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this background section qualify as prior art merely by virtue of their inclusion in this background section.